Collapsible gantry



Feb. 27, 1940, a. JACOBY :rr AL COLLAPSIBLE GANTRY Filed Oct. 17, 1936 2 Sheets-Sheet 1 EMK K mus E TEL N ME R N U m m T MM A mm W AW m A Feb. 27, 1940. B. JACOBY El AL COLLAPSIBLE GANTRY Filed Oct. 17, 1936 2 Sheets-Sheet 2 //v VEN TEES. BENJAMIN L/Aaas )4 JOHN M. QU/G'LE X Patented Feb. 27, 1940 A uni TED sTA-rss PATENT OFFICE ooLLArsInLE GaN'rnY Benjamin Jacoby and John. M. Quigley, Marion,

Ohio, Company,

assignors to The.

Marion, Ohio, a corporation of Marion Steam Shovel Ohio (Incorporated in 192'!) Application October 17 24 Claims.

This invention relates to a collapsible gantry for excavating machines or other machines having booms.

The ordinary excavating machine has a forwardly and upwardly inclined boom which is usually supported at a fixed inclination but which. is adjustable to diilerent inclinations according to the demands of the work. This boom is supported from a gantry, sometimes called an A-frame, which ismounted on the platform of the machine, usually by means of a cable which is connected with the point of the boom and extends about a sheave on the gantry to a=hoisting drum on the platform, whereby the ,vertical movement of the boom may be controlled and it may be adjusted to the desired inclination. The height of this gantry is limited by the fact that the machine in traveling from one point to another must pass under overhead structures, wires and the like which would obstruct the movement of a high gantry. The ordinary gantry provides a satisfactory support for the boom in its higher elevations but when the boom is lowered to a position in which its point is near the level of the top ofthe gantry the cable comes so'nearly-p rallel to the boom that it does not factory support and it places the, boom der.

relatively great compression stresses. 'It is'there' fore highly desirable, particularly in the-'casetojf booms of relatively great length, to provide a, that the cable will v extend in all positions of the latter, as to provide asatisiactory support' gantry of such'height at such an angle to the'boom,

therefor and to avoid undue stresses.-

It is the primary object of";my-'invention to provide a gantry of relativelygreat height which will be collapsible to permitit to .passunder overhead structure under whichlthelnsual gantry could pass. 1

A further object-of the invent ona ts-prance a collapsible gantry ofs'uch'a- 'character that it, can be easily and quickl'ycol psedtojpermitthe machine-to pass under'an o'v rhead structure-and then-quickly andeasily -restored to its extended position.

A further object 61 the inventionis toxproyide.

' a collapsible gantry of' such a characterithat it will support the boom whilein its"col.lapaedconjdition, thereby permitting the machine and the boom, as a whole,-to' be moved-under 'the'ove'rhead structure.

A further object a collapsible gantry the several parts of which will be so constructed and arrangedthat no part of the structure'can contact with the boom in provide a satisthat this embodiment of the invention has been of'the invention is to proyide 1936, Serial No. 106,151

any position to which the gantry may be moved.

A further object of the invention is to provide a gantry of such construction that it may be installed on existing machines by the addition of 'parts tothe ordinary gantry, with little or no clrfimge invthat gantry or other parts of the mac ne.

such a collapsible gantry which will be simple in its construction, of a strong rigid character and which may be produced at a relatively low cost. 7 Other objects of the invention may appear as the device is described in detail.

In the accompanying drawings Fig. 1 is aside elevation of the forward portion of a dragline excavator', partly broken away, showing a collapsible gantry installed thereon; Fig. 2 is a side elevation of a portion of the machine, partly broken away, showing the boom supported in an elevated position by the partly collapsed gantry; and Fig. v 3 is a transverse section of the gantry taken on the line 3-4 of Fig. 1. I

In these drawings we have illustrated one embodiment of our' invention and have shown the I same as, applled'to a dragiineexcavator or a well.

known construction but it will be understood choserilfor the purpose-of illustration only and that the gantry may take various forms and may be applied to.excavating machines orother methe spirit of the invention.

p The machinehere-shown is a dragline of ordinary "construction and comprises a base it carriedj by" suitable; traction devices II and having mounted, hereon a rotatable platform II on 'anism are mounted, the machinery being enclosed in la housing'iii; A, boom I4 is mounted at its foot 'upon the platform I! and an excavating scoop-i5 is/supported from'the'point of the boom ontlieboorri and: thence rearwardly to the platiorm' where: it, isywound on a power operated v drum, which is not here shown but which I is mounted on ai'shaftx Il. The scoop is moved through'thematerial to beexcavated, toward the fmachine, by a .drag cablev I! connected with the ope'n-en'djof the scoop, by means of a bridle 2t and wound on a power operated a drumalso mounted on the'shaft It. The two drums are separately operable to firstv till the scoop and then hoist the same to permit it to be. moved to dumping position by swinging the boom.

A further object of the invention is to provide which'lthe 'variousparts oi the: excavating mech-' y; 3 1519 lijwhich extends about a sheave Il- The boom is supported at the desired inclinacliines of various kinds, without departing from tion by means of a cable 22 connected with the boom and extending about a sheave on a gantry to a hoisting drum 23 which controls the movements of the cable and thereby the position of the boom. In order that the cable may be supported at a sufficient height to maintain the same at a relatively'broad angle to the "boom in all positions of the.latter-without interfering with the movement of the machine as a whole beneath overhead structures, we have provided a collapsible gantry, be collapsed or will not interfere with the passage of the machine beneath such overheadstructures. As here shown, the gantry comprises a lower or base structure mounted on the platform l2 and, in the present instance, consisting of an upright member 24, here shown as slightly inclined, and a forwardly and downwardly extending member or brace which is connected at its upper end with the upright member 24 and at its-lower end with a fixed part on the platform l2. The members 24 and 25 may be of any suitable construction but'preferably each member comprises a pair of upright bars spaced laterally one from the other, as shown in Fig. 3; This base struc ture is provided'at its upper end with a sheave 26 which is preferably mounted on a shaft 21 carried by the upper portion of the base structure and which, in the present instance, also serves to connect the members 24, and 25 one with the other. shown is substantially identical with the gantry with which such a machine is usually provided and such ordinary gantry may, if desired, be

utilized as the base stru'cture of the collapsible I gantry, or a separate base structure may be provided. In the present construction the collapsible parts of the gantry are of such a character that they may be mountedon the ordinary rigid gantrinthus enabling that gantry to be converted into a collapsible gantry by the addition of the collapsible'parts thereof,.which may be done in the field without the necessity of returning the-machine to the shop, as little or no change in construction is required.

The upper or collapsible portion of the gantry comprises a supportingmember 28 which extends upwardly from the base structure and is so mounted thereon that it can be moved from an upright position above the base structure to a position in which it will not'extend above'the' top of the base structure. Preferably this supporting member is pivotally mounted at its lower end on the base structure and; in the arrangement shown, it comprises two pairs of bars spaced one from the other and pivotally mounted on the.

shaft 21 near the respective ends thereof. Any suitable means may be provided for normally locking this supporting member in its extended or upright position but preferably'thi's means is.

in the form of a brace extending from the upper portion of the supporting member to a fixed support on or adjacent to the platform l2. In the construction shown this brace comprises two members 29 and 30 which are normally alined one with the other to provide a rigid brace but which are pivotally connected one to the other and with the supporting member and a stationary part of the machine in such a manner as to perm'it them to fold one toward the other and thereby cause the supporting member to move about its axis. In the present instance each brace member comprises two bars spaced laterally one from the other and the adjacent ends of the corthe upper portion of which may. folded to a position in which it The base structure as .here

strength to withstand the compression stresses.

to which they 'are subjected. The upper ends of the bars of the upper brace member 29 are pivotally mounted on a shaft 32 mounted on the upper end of the supporting member 28 and the lower ends of the two bars of the lowerbrace member 30 are pivotally mounted at 33 on parts of the base structure adjacent-to j'the platform I2. The upper brace member 29, is provided with short arms 34 which extend downwardly below the pivot point 3| and are provided with lugs 35 which overhang. the forward side of the lower brace member 30 to prevent the connected ends of the two members from moving rearwardly beyond other, alined positions. Suitable means are provided for positively holding the brace members normally against forward movement, this means being preferably interposed between the brace and the base structure of the. gantry.

-As here shown, tie bars or links 36 are pivotally mounted on the shaft 21 ofv the base structure and are detachably connected with the lower brace member 30, as by means of'pins 31 extending through lugs 38 carried by that brace member and removable therefrom to permit the forward movement of the brace members about their axes. The gantry isprovided at the upper end of the supporting member'28 with asheave 39, preferably mounted on the shaft 32; about which the boom cable 22 extends. Usually this v boom cable is dead ended on the supporting member 28, as by rigidly securing the end thereof to a connecting device 40 pivotally mounted on the shaft 32.

boom. and then rearwardly about the sheave 33 and downwardly to the hoisting drum 23. The

cable may be reeved back and forth between the connecting device and the point of the boom any suitable number of times by providing the boom with additional sheaves 4l and mounting hori--' zontal sheaves on the connecting device but so far as the present invention is concerned it is immaterial how the cable is mounted so long as it is connected with the boom and extends about the sheave on the gantry.

It will be apparent that the two part brace constitutes a toggle which, when in its extended position, rigidly retains the supporting member 28 in its upright'or operative position. when this supporting member is .to be lowered or collapsed the toggle is brolgen by moving the conne'cted ends of the two brace members forward- The cable then extends for wardly about a sheave 4| near the point of the transferred to the sheave 26 and the base struc-.

ture, a guide 42 being provided to cause the cable to properly engage the sheave 23. 'I'he.sup-

porting member 28 then moves into alinement with that portion of the boom cable between the connecting device 40 and the point of the boom and thereafter serves merely as a part of the means for connecting the cable with the base structure of the gantry, and the cable can be When -theboom 'boom may operated over the lower sheave 28 to control the position of the boom in the same manner that it would beoperated it the extension or collapsible elements were not present.

When the gantry is to be collapsed the boom may, if desired, be lowered to support the point thereof on'the ground, or other suitable support, or the gantry may be collapsed while the boom is supported by the boom cable 22. If the boom is lowered onto a support the load on the boom cable is, of course, relieved and when the toggle is moved to its releasing position the movable parts of the gantry will move downwardly by gravity, the drum 23 being operated totake up the slack in the boom cable as the supporting member 28 and its sheave 39 move downwardly. Whenthegantry is collapsed while the boom is supported by the cable 22 the drum 23 is operated to slowly lower the boom, after the brace has been released, and the movable parts of the gantry will move downwardly with the boom. To

prevent the too rapid collapsing of the gantry, which might cause injury to parts of the machine, we prefer to provide means for retarding that movement, such as a cable connected with the brace and with a power operated drum, so that the collapsing movement of the gantry. may be retarded by slowly paylng'out the cable and the gantry may be restored to its extended posi tion by winding in the cable. To avoidthe necessity of providing an additional cable and operatingmechanism therefor the-dragline cable i9 may be used as a retarding and restoring cable by disconnecting the same from the bridle 20 of the scoop, passing the same over a sheave 43 on the shaft 21 of the basestructure and connecting the same with a, bridle-4Q" on the lower brace member 30., The drag cableisusually connected with {the bridle 20'T" by'3means ,ot 9. socket 45 in which the ;end-;'of. the fcable is'secured by a wedge in'the *ordinarymanner. In-

asmuchv as this socketgwlll not pass between the sheaves 0f the-fair leadf -it is preferable to' remove the wedge and' disconnect the cable from the 1 socket l5" and toj-thenk-connect the same with the bridle l4 ofthe'bracemember. by wedgingithe end thereoi in a-g siinilar socket," on the bridle I I I p v has been lowered onto a support and the gantry-collapsed the point of the be raised, by the boom cable 22 to a slightly elevated position so that it will be wholly supported by the machine and the machine as a whole, including the boom, may be propelled from one position to another. when the boom is supported on the ground the gantry may be restored =to'its extended position by winding in the retarding and restoring cable I! and paying out the boom cable 22 to permit the collapsible supporting member 28 to move to its upright position while the boom remains stationary. The boom when in its lowered position may be supported either on'the ground or by the boom cable and lt'may be moved from its lowered position to any desired elevation by the action of the boom cable. -As the boom is elevated the movable parts of the gantry will move with the boom toward their extended positions, and the movement of the gantry to its fully extended position may be completed either by the retarding and restoring cable or by the boom.

A considerable force is required to move the I two members of the brace about their axis 3| to break t toggle, especially when the weight of the boom is supported by the cable 22 and the gantry. It is therefore desirable to provide some means for imparting this initial movement to the brace members. This may be conveniently done by means of a small jack interposed between one of the brace members and a relatively stationary part. We have here shown such a jack in the form of a turnbuckle 48 which is pivotally mounted at one end on the base structure of the gantry and at its other end engages the lower brace member 30 when the latter is in its operative position but is detachably connectgl with that brace member to permit the latter'to move with relation thereto after initial movement has been imparted to the brace.

It will be obvious from the foregoing description that when the gantry is in its collapsed or partially collapsed position the weight of the boom' is carried by the base structure of the gantry and that the boom may be supported by the cable 22, operating over the sheave 26 in any desired position and the excavating element can be operated while the boom is so supported, thereby enabling small excavating jobs to be done between successive movements of the machine. without the necessity of restoring the gantry to its extended position, as shown in Fig. 2.

It is important that the collapsible elements of the gantry shall not contact with the-boom in any position to which the boom and gantry may be moved. To prevent this the several parts of the gantry must be carefully proportioned and the pivotal axes of the movable parts so arranged that the movable parts of the gantry, and particularly the connected ends of the two brace members, will at all times be spaced from the boom The proportions. of the parts and the arrangement of the pivots as here shown are well adapted for this purpose but obviously the proportions may be changed and the arrangement of the pivots varied to" accommodate the same to difierent installations or to different embodiments of the invention.

While we have shown and described one embodiment of our invention we wish it to be understood that we do not desire to be limited to the details thereof as variousmodifications may occur to a person skilled in the art.

Having now fully described our invention,

what we claim as new and desire to secure by Letters Patent, is: r

,1. In a machine comprising a boom, a cable to support said boom, and means for taking in or paying out said cable to raise or lower said boom, a gantry including a stationary structure and a member mounted on said stationary structure for movement thereon from an elevated position to a lower position, a sheave carried by said movable member, and means for retaining said movable member normally in said elevated position with said sheave in supporting engagement with said cable, said retaining means including a part which is movable while said cable is supported on said sheave to release said boom, a gantry including a stationary structure elevated position with said sheave in supporting engagement with said cable, said movable member being so arranged that when released from said retaining means it may move downwardly either during the downward movement of said boom or while said boom is supported independently of said cable.

3.,In a machine comprising a boom, a' cable to support .said boom, and means for taking in or paying out said cable to raise or lower said and a member mounted'on said stationary structure for movement-thereon from an elevated position to a lower position, a sheave carried by said movable member, and means for retaining said movable member normally in said elevated position with said sheave in supporting engagement with said cable, said retaining means including a part which is movable while said cable is supported on said sheave to release said movable member for downward movement, and means to control the movement of said movable member.

4. In a machine comprising a boom, a cable to supportsaid boom, and means for taking in or paying out said cable to raise or lower said boom, a gantry including a stationary structure and a member mounted on said stationary structure for movement thereon from an elevated position to a lower position, a sheave carried by said movable member, and means for retaining said movable member normally in said elevated position with said sheave in supporting engagement with said cable, said retaining means including a part which is movable while said cable is supported on said sheave to release said movable member for downward movement, and a sheave carried by said stationary structure and arranged to receive said cable as said movable member moves downwardly.

' 5. In a machine comprising a boom, a cable to support said boom, and means for taking in or. paying out said cable to raise or lower said boom, afgantry having a movable member, a sheave carried by said movable member, releasable means for retaining said movable member normally in an elevated position with said sheave in supporting engagement with said cable, said movable member being so mounted that when released from said retaining means it may move downwardly either during or subsequent to the downward movement of said boom, and means to control said downward movement of said movable member.

6. In a machine comprising a boom, a cable to support said boom, and means for taking in or paying out said cable to raise or lower said boom, 2. gantry .having a movable member, a sheave carried by said movable member, releasable means for retaining said movable member normally in an elevated position with said sheave in supporting engagement with said cable, said movable member being so mounted that when released from said retaining means it may move downwardly either during or subsequent to the downward movement of saidboom, and means acting on said movable member to retard its downward movement and to restore the same to its elevated position. r

7. In axmachine comprising a boom, a cable to support said boom, and means. for taking in or paying out said cable to raise or lower said boom, a gantry having a base and a member pivotally mounted on said base, a sheave carried by said pivoted member, and releasable means for normally retaining said pivoted member in an engagement with said cable, said pivoted member ried by said-base and arranged to receive said memberin said upright'position with saidsheave in supporting; engagement.-'with ,saidcable, said zontal position while said boom moves down- 5 wardly under the control of said cable. I

8. In a machine comprising a boom, a cable I to support said boom, and means for taking in or paying out said cable to raise or lower said boom, a gantry having a base and a member pivotallyniounted on said base, a sheave carried by said. pivoted member, releasable means for normally retaining said pivotedmember in an upright position with said sheave in supporting being so arranged that when released by said retaining means it may move toward a horizontal position while said boom moves downwardly un- I der the control of said cable, and a sheave car' cable as the first mentioned sheave moves toward said horizontal position. a

9. In a machine-comprising a boom, a cable to support said boom, and means for taking in or paying out said cable to raise or lower said boom, a gantry having a base and'a memberpivotally mounted on said base, asheave carried by said pivoted member, releasable-means for normally retaining said pivotedgmember in an upright position with-saidtsheave in supporting engagement with saidc-ableisaid pivoted "member I being so arranged thatgwhenreleased by said retaining means it may move toward a horizontal position while said boom moves downwardly under the controlof said cable, and means to con'- trol the movement of said pivotal member about its pivotal axis. v

10. In a machine comprising a boom', a cable to support said boom, and means for taking in or paying out said cable to raise or lower said boom, pivotally mounted on said base, a sheave carried by said pivoted member, releasable means for normally retaining said pivoted member in an upright position withv said sheave in supporting engagement with said cable, said pivoted member being so. arranged that when released by said retaining means it may move toward a horizontal position while said boom moves downwardly under the control of said cable, and a cable acting on said pivoted member to retardits downward movement and to thereafter, restore the same to its upright position.

11. In a-machinecomprising a boom, a cable to support said boom, 'and i'neansfor taking in or paying out said cable toraise or lower said boom, a gantry having amember pivotally toward said boom, a sheavecarried by said member, anda toggle brace for'rigidly'supporting said toggle brace being soarranged that'the breaking downwardly toward said 12. In a machine comprisinga boom, a to support said boom, and means ifortaking inw of'the toggle will permit saidilmemb'erto mov r, I

or paying out said cable to raise or. lower said boom,.a gantry havinga memberpivotally mounted for movement 'from an upright position '10 toward said boom, a sheave carried by'said-memher, a toggle brace for rigidly supporting said member in said upright position with said sheave in supporting engagement with'saidcable, said toggle brace being so arranged that the breakingfll a gantry having a base and a member [68 cable of the toggle will permit said member to move downwardly toward said boom. and means acting on said toggle brace to control the downward movement of said pivoted member.

13. In a machine comprising a boom, a cable to support said boom, and means for taking in or paying out said cable to raise or lower said boom, a gantry having a member pivotally mounted for movement from an upright position toward said boom, a sheave carried by said member, a toggle brace for rigidly supporting said member in said upright position with said sheave in supporting engagement with said cable, said toggle brace being so arranged that the breaking ofthe toggle will permit said member to move downwardly toward said boom, and means acting on said toggle brace to break the toggle and release said pivoted member. s

14. In a machine comprising a boom, a cable to support said boom, and means for taking in or paying out said cable to raise or lower said boom, a gantry having a base and a member pivotally mounted on said base for movement from an upright position toward said boom, an upper sheave carried by said pivoted member, a lower sheave carried by said base, a toggle brace to normally support said pivoted member in an upright position with said upper sheave in supporting engagement with said cable, means to break said toggle and release said pivoted membet for downward movement toward said boom, said movement of said pivoted member causing said cable to have supporting engagement with said lower sheave, and means acting on said toggle brace to retard the downward movement of said pivoted member.

15. In a machine comprising a boom and a cable to control the vertical movement of said boom, a gantry having a base and .a member pivotally mounted on saidbase for movement from an upright position toward said boom, an upper sheave carried by said pivoted member, a lower sheave carried by said base, a toggle brace to normally support said pivoted member in an upright position with said upper sheave in supporting engagement with said cable, meansto break said toggle and release said pivoted member for downward movement toward said boom, said movement of said pivoted member causing said cable to have supporting engagement with said lower sheave, a cable connected with said toggle brace, and power controlled means acting on said cable to retard the downward movement of said pivoted member and to thereafter extend said toggle brace and restore said pivoted member to its upright position.

16. In a machine comprising a boom, a hoisting drum and a cable connecting said hoisting drum with said boom to control the vertical movement of the latter, a gantry having a movable member, a sheave carried by said movable member, releasable means for normally retaining said movable member in an elevated position with said sheave in supporting engagement with said cable and for releasing said movable memher for downward movement, means cooperating with said cable to enable the latter to control the position of said boom after downward movement has been imparted to said movable member, and means to control the movement of said movable member.

17. In a machine having a platform and a boom, a gantry comprising a base structure carried by said platform, a supporting member pivotally mounted on said base structure for movement from a normally upright position toward said boom, a sheave carried by said supporting member, a hoisting drum on said platform, a cable connected with said boom and extending about said, sheave to said drum, a brace to retain said supporting member in its upright position, said brace having two parts pivotally connected one with the other, one part of said brace being pivotally connected with said supporting member and the other part of said brace being pivotally connected with a normally stationary part of said machine, whereby the movement of the conneoted ends of said parts of said brace toward said boom will permit said supporting member to move toward a horizontal position, and means.

to retard the movement of said brace and said supporting member.

18, In a machine having a platform and a boom, a gantry comprising a base structure carried by said platform, a supporting member pivotally mounted on said base structure for movement from anormally upright position toward said boom, a sheave carried by said supporting member, a hoisting drum on said platform, a cable connected with said boom and extending about said sheave to said drum, a brace to re tain said supporting member in its upright position, said 'brace having two parts pivotally connected one with the other, one part of said brace being pivotally connected with said supporting member and the other part of said brace being pivotally connected with a normally stationary part of said machine, whereby the movement" of the connected ends of said parts of said brace toward said boom will permit said supporting member to move toward a horizontal position, a second drum carried by said platform, a cable wound on said second drum, and means for con necting said cable with said brace to control the movements thereof.

19. In a machine having aplatform and a boom carried by said platform, a collapsible gantry comprising a base structure on said platform, a normally upright supporting member pivotally mounted on said base structure, means for establishing supporting connection between said boom and said member when the latter is in its upright position, and a brace connected at its respective ends with said supporting member and with a stationary part of said machine and comprisingtwo alined members having their adjacent ends pivotally connected one to the other and movable toward said boom to collapse said gantry, the several parts of said gantry being so proportioned and having their pivotal axes so arranged that the connected ends of said brace members will be supported out of contact with said boom in all operative positions of said boom and said brace.

20. In a machine having a platform and a boom carried by said platform, a collapsible gantry comprising a base structure on said plat form, a normally upright supporting memben pivotally mounted on said base structure and movable toward said boom, means for establishing supporting connection between said boom and said member when the latter is in its upright position, and a brace connected at its respective ends with said supporting member and with a stationary part of said machine and comprising two alined members having their adja-- cent ends pivotally connected one to the other and movable toward said boom to collapse said gantry, and detachable means for rigidly connecting said brace with said base structure to Kid retain said brace members in their alined positions'.

21. In a machine having a platform and a boom carried by said platform, a collapsible gantry comprising a base structure on said platform, a normally upright supporting member pivotally mounted on said base structure, means for establishing supporting connection between said boom and said member when the latter is in its upright position, and a brace connected at its respective ends with said supporting member and with a stationary part of said machine and comprising two 'alined members having .their adjacent ends pivotally connected one to the other and movable toward said boom to collapse said gantry, and a device interposed between said base structure and said partsand acting on the latter to impart initial movement thereto. '22. Ina dragline excavator comprisinga platform, a boom carried by said platform, an excavating scoop, a cable to support said scoop from v. the point of said boom, a drag cableto impart I v excavating movement to said scoop and power operated drums on said platform to operate said;

cables, a, collapsible gantry including a] has structure, a normally upright supportlng mem ber pivotally mounted on saidbase structure,-' foldable brace having alinedvmembers piyotal connected one with the other and plvotally con nected respectively with said supporti'n nmemberw andwith a stationary parteon said platform, af sheave on said base structure adapted to receive said drag cable when the latter has be'en-rletached from said. scoom means for connecting}; said dragcable with said brace tocontrolithef movements thereof, a sheave on said supporting; member, acable connected with saidboom and; extending about the last mentioned sheave, and l by said supporting member and adapted o:r

;:'colla psed positions;

means on said platform for controlling the movements of the last mentioned cable.

23. An attachment for a machine having a platiorm, a boom, a hoisting drum, a gantry, a

sheave carried by said gantry and a cable con- 5 ceive. and support 'said'cablewhen said support: 7 ing member is'in, lt's upright position and soar. rangedthat 'saidi cable will be automatically l0- transferredltherefro to the sheave on said gan--' ing member movesirom v. has: out a vertical axlsoverthe 85] oarria'gei 'a 'boomiat the 'front of the.( :ab, Iamast 1 1 18511 I w -cabgback of the boom; and com-q I prising aj i section ofv substantiallyA-rrame formation-,;an upper section having its lower ill-f ner end pivoted to" the upper end of the lower 89' section, and 'a -upport for. the uppersection rislngirom the carriage between the boom and'ithe lower sectionand comprising movablepartscon-f nected ,onelto the other 'i'or relative movement to a "nests; uonamgoWc-neg, 

